#ifndef __BLENDMODE_H__
#define __BLENDMODE_H__


#include "U2PreRequest.h"
#include "U2ColourValue.h"


U2EG_NAMESPACE_BEGIN


/** Type of texture blend mode.
*/
enum LayerBlendType
{
    LBT_COLOUR,
    LBT_ALPHA
};

/** List of valid texture blending operations, for use with TextureUnitState::setColourOperation.
@remarks
    This list is a more limited list than LayerBlendOperationEx because it only
    includes operations that are supportable in both multipass and multitexture
    rendering and thus provides automatic fallback if multitexture hardware
    is lacking or insufficient.
*/
enum LayerBlendOperation {
    /// Replace all colour with texture with no adjustment
    LBO_REPLACE,
    /// Add colour components together.
    LBO_ADD,
    /// Multiply colour components together.
    LBO_MODULATE,
    /// Blend based on texture alpha
    LBO_ALPHA_BLEND

};

/** Expert list of valid texture blending operations, for use with TextureUnitState::setColourOperationEx
    and TextureUnitState::setAlphaOperation, and internally in the LayerBlendModeEx class. It's worth
    noting that these operations are for blending <i>between texture layers</i> and not between rendered objects
    and the existing scene. Because all of these modes are only supported in multitexture hardware it may be
    required to set up a fallback operation where this hardware is not available.
*/
enum LayerBlendOperationEx {
    /// use source1 without modification
    LBX_SOURCE1,
    /// use source2 without modification
    LBX_SOURCE2,
    /// multiply source1 and source2 together
    LBX_MODULATE,
    /// as LBX_MODULATE but brighten afterwards (x2)
    LBX_MODULATE_X2,
    /// as LBX_MODULATE but brighten more afterwards (x4)
    LBX_MODULATE_X4,
    /// add source1 and source2 together
    LBX_ADD,
    /// as LBX_ADD, but subtract 0.5 from the result
    LBX_ADD_SIGNED,
    /// as LBX_ADD, but subtract product from the sum
    LBX_ADD_SMOOTH,
    /// subtract source2 from source1
    LBX_SUBTRACT,
    /// use interpolated alpha value from vertices to scale source1, then add source2 scaled by (1-alpha)
    LBX_BLEND_DIFFUSE_ALPHA,
    /// as LBX_BLEND_DIFFUSE_ALPHA, but use alpha from texture
    LBX_BLEND_TEXTURE_ALPHA,
    /// as LBX_BLEND_DIFFUSE_ALPHA, but use current alpha from previous stages
    LBX_BLEND_CURRENT_ALPHA,
    /// as LBX_BLEND_DIFFUSE_ALPHA but use a constant manual blend value (0.0-1.0)
    LBX_BLEND_MANUAL,
    /// dot product of color1 and color2 
    LBX_DOTPRODUCT,
    /// use interpolated color values from vertices to scale source1, then add source2 scaled by (1-color)
    LBX_BLEND_DIFFUSE_COLOUR
};

/** List of valid sources of values for blending operations used
    in TextureUnitState::setColourOperation and TextureUnitState::setAlphaOperation,
    and internally in the LayerBlendModeEx class.
*/
enum LayerBlendSource
{
    /// the colour as built up from previous stages
    LBS_CURRENT,
    /// the colour derived from the texture assigned to this layer
    LBS_TEXTURE,
    /// the interpolated diffuse colour from the vertices
    LBS_DIFFUSE,
    /// the interpolated specular colour from the vertices
    LBS_SPECULAR,
    /// a colour supplied manually as a separate argument
    LBS_MANUAL
};
/** Class which manages blending of both colour and alpha components.
@remarks
    This class is a utility class used by both TextureUnitState and
    RenderSystem to wrap up the details of a blending operation. This blending
    operation could be used for blending colour or alpha in a texture layer.
    This class is really only for use by OGRE, since apps can deal with
    blending modes through the TextureUnitState class methods
    setColourOperation and setAlphaOperation.
@par
    It's worth noting that these operations are for blending <i>between texture
    layers</i> and not between rendered objects and the existing scene. If
    you wish to make an object blend with others in the scene, e.g. to make
    transparent objects etc, use the Material::setSceneBlending method.
*/
class _U2Share LayerBlendModeEx
{
public:
    /// The type of blending (colour or alpha)
    LayerBlendType blendType;
    /// The operation to be applied
    LayerBlendOperationEx operation;
    /// The first source of colour/alpha
    LayerBlendSource source1;
    /// The second source of colour/alpha
    LayerBlendSource source2;

    /// Manual colour value for manual source1
    U2ColourValue colourArg1;
    /// Manual colour value for manual source2
    U2ColourValue colourArg2;
    /// Manual alpha value for manual source1
    u2real alphaArg1;
    /// Manual alpha value for manual source2
    u2real alphaArg2;
    /// Manual blending factor
    u2real factor;

    bool operator==(const LayerBlendModeEx& rhs) const
    {
        if (blendType != rhs.blendType) return false;

        if (blendType == LBT_COLOUR)
        {

            if (operation == rhs.operation &&
                source1 == rhs.source1 &&
                source2 == rhs.source2 &&
                colourArg1 == rhs.colourArg1 &&
                colourArg2 == rhs.colourArg2 &&
                factor == rhs.factor)
            {
                return true;
            }
        }
        else // if (blendType == LBT_ALPHA)
        {
            if (operation == rhs.operation &&
                source1 == rhs.source1 &&
                source2 == rhs.source2 &&
                alphaArg1 == rhs.alphaArg1 &&
                alphaArg2 == rhs.alphaArg2 &&
                factor == rhs.factor)
            {
                return true;
            }
        }
        return false;
    }

    bool operator!=(const LayerBlendModeEx& rhs) const
    {
        return !(*this == rhs);
    }

};

/** Types of blending that you can specify between an object and the existing contents of the scene.
@remarks
    As opposed to the LayerBlendType, which classifies blends between texture layers, these blending
    types blend between the output of the texture units and the pixels already in the viewport,
    allowing for object transparency, glows, etc.
@par
    These types are provided to give quick and easy access to common effects. You can also use
    the more manual method of supplying source and destination blending factors.
    See Material::setSceneBlending for more details.
@see
    Material::setSceneBlending
*/
enum SceneBlendType
{
    /// Make the object transparent based on the final alpha values in the texture
    SBT_TRANSPARENT_ALPHA,
    /// Make the object transparent based on the colour values in the texture (brighter = more opaque)
    SBT_TRANSPARENT_COLOUR,
    /// Add the texture values to the existing scene content
    SBT_ADD,
	/// Multiply the 2 colours together
	SBT_MODULATE,
    /// The default blend mode where source replaces destination
    SBT_REPLACE
    // TODO : more
};

/** Blending factors for manually blending objects with the scene. If there isn't a predefined
    SceneBlendType that you like, then you can specify the blending factors directly to affect the
    combination of object and the existing scene. See Material::setSceneBlending for more details.
*/
enum SceneBlendFactor
{
    SBF_ONE,
    SBF_ZERO,
    SBF_DEST_COLOUR,
    SBF_SOURCE_COLOUR,
    SBF_ONE_MINUS_DEST_COLOUR,
    SBF_ONE_MINUS_SOURCE_COLOUR,
    SBF_DEST_ALPHA,
    SBF_SOURCE_ALPHA,
    SBF_ONE_MINUS_DEST_ALPHA,
    SBF_ONE_MINUS_SOURCE_ALPHA

};

/** Blending operations controls how objects are blended into the scene. The default operation
	is add (+) but by changing this you can change how drawn objects are blended into the
	existing scene.
*/
enum SceneBlendOperation
{
	SBO_ADD,
	SBO_SUBTRACT,
	SBO_REVERSE_SUBTRACT,
	SBO_MIN,
	SBO_MAX
};


U2EG_NAMESPACE_END


#endif
